DE69808913T2 - MONOAZO DYES AND INK CONTAINING THIS - Google Patents

Description

This invention relates to dyes, inks and their use in ink jet printing (IJP). IJP is a non-mechanical printing technique in which ink droplets are ejected through a fine nozzle onto the substrate without the nozzle being brought into contact with the substrate.

EP 0 481 449 relates to an ink composition containing a water-soluble dye, an organic solvent and water.

All dyes disclosed in EP 0481449 are characterized by the presence of a group of the formula -SO₂CH₂CH₂SO₃H, which is an essential feature of the dyes.

DE 2062163 describes the production of dyes for dyeing textiles, whereby the dyes have good wash fastness.

There are many performance requirements for dyes and inks used in IJP. For example, they desirably produce sharp, non-feathered images with good waterfastness, lightfastness and optical density. The inks are often required to dry quickly when applied to a substrate to prevent staining, but they should not form a crust over the tip of an inkjet nozzle, as this would stop the printer from operating. The inks should be stable when stored for long periods of time without decomposing or forming a precipitate that could block the fine nozzle.

According to a first aspect of the invention there is provided a compound of formula (1): Formula (1)

wherein:

A is N, C-Cl, C-CN or C-NO₂;

L¹ is -OR³;

Z is -O-, -S- or -NR²-;

R¹ and R² are each independently H or optionally substituted alkyl;

R³ is H or alkyl;

each W is independently -CO₂Q or -SO₃Q;

each X is independently an optionally substituted amino group or a group substituted with an optionally substituted amino group;

each Y is independently halogen, hydroxy, nitro, cyano, optionally substituted alkyl, optionally substituted alkoxy, optionally substituted aryl, optionally substituted aralkyl, -S-Ra, -CORa, -COORa, -SO₃Ra or -SORa;

Ra is C₁₋₄alkyl optionally substituted by carboxy, sulfo, hydroxy, nitro, cyano or halogen;

each Q is independently ammonium or substituted ammonium ;

m, n and p each independently have a value from 0 to 3; and

(m + n + p) has a value from 0 to 5.

Preferably A is N.

Preferably, m, n and p independently have the value 0 or 1.

Preferably, n is 1 when m is 0.

Preferably (m + n + p) has a value of 1, 2 or 3, more preferably 1 or 2.

Z is preferably -NR²-, more preferably -NH-.

Each Y is independently halogen, more preferably F or Cl; hydroxy; nitro; cyano; optionally substituted alkyl, preferably optionally substituted C1-10 alkyl, especially C1-4 alkyl; optionally substituted alkoxy, preferably optionally substituted C1-10 alkoxy, more preferably C1-4 alkoxy; optionally substituted aryl, preferably optionally substituted phenyl or optionally substituted naphthyl; optionally substituted aralkyl, preferably optionally substituted C7-12 aralkyl, more preferably phenyl- (C1-6 alkylene)-, especially phenyl-CH2-; -SRa, -CORa, -COORa, SO3Ra or -SORa, where Ra is optionally substituted C1-4 alkyl, the optional substituents being selected from carboxy, sulfo, hydroxy, nitro, cyano and halogen.

R¹ and R² are preferably each independently H or optionally substituted C₁₋₄-alkyl, more preferably H, C₁₋₄-alkyl or C₂₋₄-alkyl substituted by hydroxy, carboxy, sulfo or cyano. Examples include methyl, ethyl, n-propyl, isopropyl, hydroxyethyl, cyanoethyl, sulfopropyl and carboxyethyl. It is especially preferred that R¹ and R² H are.

The compounds of formula (1) are preferably monoazo compounds (i.e. they contain only one azo (-N=N-) group).

R³ is preferably H or C₁₋₁₀-alkyl, more preferably H or C₁₋₆-alkyl, especially H or C₁₋₄-alkyl, more especially H.

When X is an optionally substituted amino group or is substituted by an optionally substituted amino group the optionally substituted amino group has a pKa of from 12 to 4, more preferably from 10 to 6.

The optionally substituted amino groups referred to in the definition of X preferably have the formula -NR⁴R⁵, wherein R⁴ and R⁵ independently of one another are each H or optionally substituted alkyl or R⁴ and R⁵ together with the nitrogen atom to which they are attached form a 5- or 6-membered ring.

When R4 or R5 is optionally substituted alkyl, it is preferably optionally substituted C1-6 alkyl, more preferably optionally substituted C1-4 alkyl. Preferred substituents are selected from carboxy, sulfo, hydroxy, amino and C1-4 alkoxy.

When R4 and R5 together with the nitrogen to which they are attached form an optionally substituted 5- or 6-membered ring, they preferably form optionally substituted morpholine, more preferably optionally substituted piperazine. The substituents are preferably selected from hydroxy, carboxy, sulfo, C1-6 alkoxy, C1-6 alkyl and C1-6 alkyl substituted by hydroxy, carboxy, sulfo or an optionally substituted amino group.

A preferred substituted morpholine or piperazine ring bears a group of the formula -M-NR⁶R⁷, where M is an alkylene linking group and R⁶ and R⁷ are independently each H, C₁₋₆alkyl or C₁₋₆alkyl substituted by hydroxy, carboxy, sulfo, amino or C₁₋₄alkoxy.

M is preferably C1-6alkylene, more preferably C2-6alkylene and especially -(CH2)g-, where g is 2 to 6.

A particularly preferred substituted piperazinyl group has the formula (2): Formula (2)

wherein M, R6 and R7 are as defined above.

Preferred groups of formula (2) include:

Examples of optionally substituted amino groups include: -NH₂, -NHCH₂CH₃, -N(CH₂CH₃)₂, -NHCH₂CH₂OH, -NH(CH₂)₂N(CH₃)₂, -NH(CH₂)₂N(CH₃)₂,

When X is a group substituted by an optionally substituted amino group, it preferably comprises optionally interrupted alkylene bearing a -NR4NR5 group, wherein R4 and R5 are as defined above.

Preferably, the optionally interrupted alkylene group comprises 1, 2 or 3 C2-10 alkylene groups and 0, 1, 2, 3 or 4 interrupting groups selected from O, CO, CO2, S, SO, SO2, NH, optionally substituted phenylene, CONH and SO2NH. The interrupting groups may be attached to any of the C2-10 alkylene chains and/or may be in a terminal position in the interrupted alkylene chain.

Preferred interrupted alkylene groups having a C₂₋₁₀-alkylene chain and an interrupting group have the formula -SO₂NH-(C₂₋₁₀-alkylene)-, -NHSO₂(C₂₋₁₀-alkylene)-; -CONH-(C₂₋₁₀-alkylene)-; -NHCO-(C₂₋₁₀-alkylene)-; -[(O, S or NH)-C₂₋₁₀-alkylene]-; -SO-(C₂₋₁₀-alkylene)- and -SO₂-(C₂₋₁₀-alkylene)-.

Preferred interrupted alkylene groups having two C₂₋₁₀ alkylene chains and two interrupting groups are any two of the groups described in the previous section bonded together, especially -SO₂-(C₂₋₁₀ alkylene)-NH-(C₂₋₁₀ alkylene)-.

Q preferably has the formula +NT₄, wherein each T is independently H or optionally substituted alkyl, or two groups represented by T are H or optionally substituted alkyl and the two remaining groups represented by T together with the N atom to which they are attached form a 5- or 6-membered ring (preferably a morpholine, pyridine or piperidine ring).

Preferably, each T is independently H or C1-4 alkyl, more preferably H, CH3 or CH3CH2, especially H. Thus, Q is preferably ammonium (i.e. +NH4).

Examples of groups represented by Q include +NH4, morpholinium, piperidinium, pyridinium, (CH3)3N+H, (CH3)2N+H2, N2N+(CH3)(CH2CH3), CH3N+H3, CH3CH2N+H3, H2N+(CH2CH3)2, CH3CH2CH2N+H3, (CH3)2CHN+H3, N+(CH3)4, N+ (CH2 CH3 )4 , N-methylpyridinium, N,N-dimethylpiperidinium and N,N-dimethylmorpholinium.

A first preferred embodiment of the invention comprises a compound of formula (1) and salts thereof, wherein:

A is N;

m is 0, 1 or 2;

n is 0 or 1;

p is 0 or 1;

X has the formula -NR⁴R⁵ or is a group substituted by -NR⁴R⁵;

Y is halogen, hydroxy, cyano, C1-4 alkyl, C1-4 alkoxy, -SRa, -CORa, -COORa, -SO3 Ra or -SORa; and

R¹, R², R³, R⁴, R⁵, Ra, Q and W are as defined above .

In the first preferred embodiment, it is particularly preferred that Y is C₁₋₄-alkyl is.

A second preferred embodiment comprises a monoazo compound of formula (3): Formula (3)

wherein:

Z is -O-, -S- or -NR⁸-;

R⁸ is H or C₁₋₄alkyl optionally substituted by hydroxy, hydroxy, sulfo or cyano;

L² is -OR⁹;

R&sup9; is H or C1-4 alkyl;

each W is independently -CO₂Q or -SO₃Q;

each X¹ is -NR⁴R⁵, -SO₂-NR⁴R⁵, -SO₂(C₁₋₁₀alkylene)-NR⁴R⁵ or C₁₋₆alkyl substituted by -NR⁴R⁵;

each Y¹ is independently Cl, nitro, cyano, C₁₋₁₀alkyl or C₁₋₁₀alkyl substituted by hydroxy, carboxy, sulfo, or C₁₋₆alkoxy;

m, n and p are each independently 0 or 1;

(m + n + p) is 1, 2 or 3 and

Q, R⁴ and R⁵ are as defined above; with the proviso that n is 1 when m is 0.

In preferred compounds of formula (3), R4 and R5 are each independently H or optionally substituted C1-6 alkyl as previously described, or -NR4R5 has formula (2) as defined above.

Preferred compounds of the second embodiment comprise a compound of formula (3) as defined above wherein:

Z is -NR⁸-;

Y¹ is C1-6 alkyl;

L² is -OH or methoxy; and

R⁸, W, X¹, m, n, p, R⁴ and R⁵ are as defined above with the proviso that n is 1 when m is 0.

The compounds of formula (1) and (3) can be converted from corresponding compounds into the free acid or into the alkali metal salt form using techniques known in the art. For example, an alkali metal salt of a dye can be converted into a salt with ammonia or an amine by dissolving an alkali metal salt of the dye in water, acidifying with mineral acid and adjusting the pH of the solution to pH 9 to 9.5 with ammonia or the amine and removing the alkali metal cations by dialysis.

The compounds may be prepared in the free acid or salt form using conventional techniques for preparing azo dyes. For example, a suitable process comprises condensing a compound of formula (4) with a compound of formula L¹H: Formula (4)

wherein:

R¹, Z, A, W, X, Y, m, n, p are as defined above .

The condensation is preferably carried out in a liquid medium, more preferably in an aqueous medium and especially in water. Temperatures of 15°C to 100°C are preferred, more preferably temperatures of 60 to 90°C. A reaction time of 1 to 48 hours, more preferably 3 to 24 hours, is preferably used.

The condensation is preferably carried out in the presence of a base. The base can be an inorganic base, e.g. ammonia, an alkali metal or alkaline earth metal hydroxide, carbonate or bicarbonate, or an organic base. Preferred organic bases are tertiary amines, e.g. N-alkylated heterocycles, such as, for example, N-(C₁₋₄-alkyl)morpholine, N-(C₁₋₄-alkyl)piperidine, N,N'-di(C₁₋₄-alkyl)piperazine; tri-(C₁₋₄-alkyl)amines, e.g. triethylamine, and optionally substituted pyridines, especially pyridine.

The amount of base used can be varied between wide limits, but it is preferred to use less than 40, more preferably less than 10 and especially 3 to 5 moles for each monomer of the compound of formula (4).

After condensation, the product can be isolated from the reaction mixture by precipitating the product as a salt, e.g. by adding a suitable alkali metal salt, especially sodium chloride. Alternatively, the product can be isolated in its free acid form by acidifying the reaction mixture, preferably using a mineral acid, especially hydrochloric acid. If the product precipitates as a solid, it can be separated from the mixture by filtration.

If desired, undesirable anions can be removed from the product of the above process by dialysis, osmosis, ultrafiltration or a combination thereof.

The product of the above process can be converted to the ammonium salt or the substituted ammonium salt by the addition of ammonia, ammonium hydroxide, primary, secondary, tertiary or quaternary amine. When the base used in the condensation process is an organic amine, an excess can be used so that the compound of formula (1) is formed as the substituted ammonium salt.

The compound of formula (4) can be prepared using conventional techniques, e.g. by:

(1) Diazotization of 2-naphthylamine-1-sulfonic acid to give the corresponding diazonium salt;

(2) coupling of the diazonium salt from step (1) with 1-acetamido-8-naphthol-3,6-disulfonic acid at pH > 7, preferably at a pH of 8 to 9;

(3) alkaline hydrolysis of the product of step (2) with removal of the acetyl group;

(4) Condensing the product from step (1) with a compound of the formula:

where A is as defined above, and

(5) Condensing the product of step (4) with about 1 molar equivalent of the compound of the formula:

where z, w, x, Y, m, n and p are as defined above.

The diazotization in step (1) is preferably carried out in an aqueous medium at a pH of below 7 in the presence of a suitable diazotizing agent. Dilute mineral acid, e.g. HCl or H₂SO₄, is preferably used to achieve the desired acidic conditions. Conventionally, the diazotizing agent is formed in situ, e.g. by dissolving an alkali metal nitrite, preferably sodium nitrite, in a molar excess of mineral acid, preferably Bd. Normally, preferably, 1 mole of diazotizing agent per mole of 2-naphthylamine-1-sulfonic acid, preferably 1 to 1.25 moles, will be used in the diazotization.

The temperature of the diazotization is not critical; it can be carried out conventionally at -5ºC to 20ºC, preferably from 0 to 10ºC and especially from 0 to 5ºC.

The hydrolysis in step (3) is preferably carried out at a pH in the range of 9 to 14. The temperature during the hydrolysis is preferably 40 to 90°C.

According to a second aspect of the present invention there is provided an ink comprising:

(a) 0.01 to 30 parts of a compound of formula (1) or preferably of formula (3) as previously defined, except that Q is any cation; and

(b) 70 to 99.99 parts of a medium comprising component (i), (ii) or (iii):

(i) a mixture of water and an organic solvent;

(ii) an organic solvent which is free from water, or

(iii) a low melting point solid;

where all parts are parts by weight and the number of parts of (a) + (b) = 100.

In preferred compounds which can be used in component (a) of the ink, Q is H or an alkali metal, more preferably Q is sodium, ammonium or substituted ammonium. It is particularly preferred that Q is ammonium or substituted ammonium as previously defined in the first aspect of the present invention.

The number of parts of component (a) is preferably 0.1 to 20, more preferably 0.5 to 15, and especially 1 to 5 parts. The number of parts of component (b) is preferably 99.9 to 80, more preferably 99.5 to 85, especially 99 to 95 parts.

When the medium is a mixture of water and an organic solvent or an organic solvent free of water, component (a) is preferably completely dissolved in component (b). Component (a) preferably has a solubility in component (b) of at least 10% at 20°C. This allows the preparation of concentrates which can be used to prepare more dilute inks and reduces the risk of the dye precipitating if evaporation of the liquid medium occurs during storage.

When the medium comprises a mixture of water and an organic solvent, the weight ratio of water to organic solvent is preferably 99:1 to 1:99, more preferably 99:1 to 50:50, and most preferably 95:5 to 80:20.

It is preferred that the organic solvent present in the water-organic solvent mixture is a water-miscible organic solvent or a mixture of such solvents. Preferred water-miscible organic solvents include C₁₋₆ alkanols, preferably methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, n-pentanol, cyclopentanol and cyclohexanol; linear amides, preferably dimethylformamide or dimethylacetamide; ketones and ketone alcohols, preferably acetone, methyl ether ketone, cyclohexanone and diacetone alcohol; water-miscible ethers, preferably tetrahydrofuran and dioxane; diols, preferably diols having 2 to 12 carbon atoms, e.g. B. Pentane-1,5-diol, ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol and thiodiglycol and oligo- and polyalkylene glycols, preferably diethylene glycol; triethylene glycol, polyethylene glycol and polypropylene glycol; triols, preferably glycerol and 1,2,6-hexanetriol; mono-C₁₋₄-alkyl ethers of diols, preferably mono-C₁₋₄-alkyl ethers of diols having 2 to 12 carbon atoms, in particular 2-methoxyethanol, 2-(2-methoxyethoxy)ethanol, 2-(2-ethoxyethoxy)ethanol, 2-[2-(2-methoxyethoxy)ethoxy]ethanol, 2[2-(2-ethoxyethoxy)ethoxy]ethanol and ethylene glycol monoallyl ether; cyclic amides, preferably 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, caprolactam and 1,3-dimethylimidazolidone; cyclic esters, preferably caprolactone; sulfoxides, preferably dimethyl sulfoxide and sulfolane. The liquid medium preferably comprises water and 2 or more, especially 2 to 8, water-soluble organic solvents.

Very particularly preferred water-miscible organic solvents are cyclic amides, especially 2-pyrrolidone, N-methylpyrrolidone and N-ethylpyrrolidone; diols, especially 1,5-pentanediol, ethylene glycol, thiodiglycol, diethylene glycol and triethylene glycol; and mono-C₁₋₄-alkyl and C₁₋₄-alkyl ethers of diols, more preferably mono-C₁₋₄-alkyl ethers of diols having 2 to 12 carbon atoms, especially 2-methoxy-2-ethoxy-2-ethoxyethanol.

A preferred medium includes:

(a) 75 to 95 parts water and

(b) a total of 25 to 5 parts of one or more solvents selected from diethylene glycol, 2-pyrrolidone, thiodiglycol, N-methylpyrrolidone, cyclohexanol, caprolactone, caprolactam and pentane-1,5-diol;

where parts are parts by weight and the sum of the parts of (a) and (b) = 100.

Examples of other suitable ink media containing a mixture of water and one or more organic solvents are described in US 4,963,189, US 4,703,113, US 4,626,284 and EP 4 251 50A.

When the liquid medium comprises an organic solvent that is free of water (i.e., contains less than 1% by weight of water), the solvent preferably has a boiling point of from 30° to 200°C, preferably from 40° to 150°C, especially from 50° to 125°C. The organic solvent may be immiscible with water, miscible with water, or a mixture of such solvents. Preferred water-miscible organic solvents are the water-miscible solvents described above and mixtures thereof. Preferred water-miscible solvents include, for example, aliphatic hydrocarbons; esters, preferably ethyl acetate; chlorinated hydrocarbons, preferably CH2Cl2;; and ethers, preferably diethyl ether; and mixtures thereof.

When the liquid medium comprises a water-immiscible organic solvent, a polar solvent is preferably included as this enhances the solubility of the dye in the liquid medium. Examples of polar solvents include C1-4 alcohols. In view of the preferences set out above, it is particularly preferred that when the liquid medium is an organic solvent free of water, it comprises a ketone (especially methyl ethyl ketone) and/or an alcohol (especially a C1-4 alkanol, more especially ethanol or propanol).

The organic solvent free from water may be a single organic solvent or a mixture of two or more organic solvents. It is preferred that when the medium is an organic solvent free from water, it is a mixture of 2 to 5 different organic solvents. This allows a medium to be selected which has a good control over the drying characteristics and storage stability of the ink.

Ink media comprising an organic solvent that is free of water are particularly useful when fast drying times are required, and especially when printing on hydrophobic and non-absorbent substrates, e.g. plastics, metal and glass.

Preferred low melting point solid media have a melting point in the range of 60°C to 125°C. Suitable low melting point solids include long chain fatty acids or alcohols, preferably those with C18-24 chains, and sulfonamides. The dye of formula (1) or (3) may be dissolved in the low melting point solid or may be finely dispersed therein.

The dyes according to the present invention have a high solubility in aqueous media; accordingly it is preferred that the liquid medium is a mixture of water and a water-miscible organic solvent or several water-miscible organic solvents.

The ink may also contain additional components that are conventionally used in inkjet printing inks, such as viscosity and surface tension modifiers, pH buffers (e.g. 1:9 citric acid/sodium citrate), corrosion inhibitors, biocides, coagulation reducing additives and surfactants, which may be ionic or non-ionic.

The presence of impurities in an inkjet printing ink can lead to the formation of precipitates in the ink. This is undesirable because the precipitates which may block the narrow ink jet gland in the printer. Therefore, the dye(s) according to the invention may be purified to remove undesirable impurities before being incorporated into inks for ink jet printing; preferably, this is done. Conventional techniques may be used to purify the dye(s), e.g. osmosis and/or dialysis.

A third aspect of the present invention provides a method of printing an image on a substrate, which comprises applying an ink according to the second aspect of the present invention to the substrate using an inkjet printer.

Preferred inks used in this process contain a dye of formula (1) or formula (3) as defined in the first aspect of the present invention.

The inkjet printer preferably applies the ink to the substrate in the form of droplets ejected through a small orifice. Preferred inkjet printers are piezoelectric inkjet printers and thermal inkjet printers. In thermal inkjet printers, programmed heat pulses are applied to the ink in a reservoir by means of a resistor adjacent to the orifice, causing the ink to be ejected in the form of small droplets directed against the substrate during relative movement between the substrate and the orifice. In piezoelectric inkjet printers, the oscillation of a small crystal causes the ink to eject from the orifice.

The substrate is preferably paper, plastic, a textile, metal or glass, preferably paper, an overhead Projector, object glass or a textile material, especially paper.

Preferred papers are plain paper or treated papers that have an acidic, alkaline or neutral character. Examples of commercially available papers include HP Premium Coated Paper, HP Photophapier (all available from Hewlett Packard Inc.), Stylus Pro 720 dpi Coated Paper, Epson Photo Quality Glossy Film, Epson Photo Quality Glossy Paper (available from Seiko Epson Corp.), Canon HR 101 Hig Resolution Paper, Canon GP 201 Glossy Paper, Canon HG 101 High Gloss Film (all available from Canon Inc.), Wiggins Conqueror paper (available from Wiggins Teape Ltd.), Xerox Acid Paper and Xerox Alkaline paper, Xerox Acid Paper (available from Xerox).

A fourth aspect of the present invention provides a paper, an overhead projector slide or a textile material printed with an ink according to the second aspect of the present invention or by the method according to the third aspect of the present invention.

If the substrate is a textile material, the ink according to the present invention is applied thereto by

(i) the ink is applied to the textile material using an inkjet printer and

ii) the printed textile material is heated at a temperature of 50ºC to 250ºC.

Preferred textile materials are natural, synthetic and semi-synthetic materials. Examples of preferred natural textile materials include wool, silk, fur and cellulosic materials, especially cotton, jute, Hemp, flax and linen. Examples of preferred synthetic and semi-synthetic materials include polyamides, polyesters, polyacrylonitriles and polyurethanes.

Preferably, the textile material has been pretreated with an aqueous pretreatment composition comprising a thickener and optionally a water-soluble base and a hydrotrope and dried prior to step i) above.

The pretreatment composition preferably comprises a solution of the base and the hydrotrope in water containing the thickener. Particularly preferred pretreatment compositions are described in more detail in European Patent Application EP-A-534660.

A fifth aspect of the present invention provides an inkjet printer cartridge containing an ink according to the second aspect of the present invention. The inkjet printer cartridge is optionally refillable.

The invention is further illustrated by the following examples, in which all parts and weights are by weight unless otherwise stated.

EXAMPLE 1 dye

Dye (1) was prepared using the procedure described below: Dye (1)

Level (i)

2-Naphthylamine-1-sulfonic acid (0.304 M, 67.84 g at 100%) was added to water (500 mL) and cooled to 0-5°C. Concentrated HCl (150 mL) was then added, followed by 2 N NaNO2 (150 mL). The solution was stirred for 1 h at 0-5°C and excess NaNO2 was destroyed by addition of sulfamic acid.

To the above solution was added 1-acetamido-8-naphthol-3,6-disulfonic acid (0.304 M, 109.83 g at 100%) in water (500 mL). The pH was then raised to 7.0 by the addition of concentrated NaHO solution and the solution was stirred at 0 to 5°C for 3 hours. The solution was then adjusted to 1.5 M NaOH by the addition of NaOH pellets and heated to 85°C for 6 hours.

The pH was reduced to 7.0 by adding concentrated HCl and the solution was adjusted to 20% salinity with NaCl. The resulting precipitate was filtered, washed and dried. The concentration was estimated to be 71.6%.

Stage (ii)

The product of step (i) above (86.5 g, 0.1 mol at a concentration of 71.6%) was dissolved in water (800 mL). Cyanuric chloride (19.36 g, 0.105 mol) was dissolved in acetone (200 mL) and added to ice/water (300 g). To this was added the solution of the product of step (i), causing the pH to fall. The resulting solution was stirred at 0 to 5°C for 2 hours. Then the pH was raised to 7.0 by the addition of 2 N NaOH solution and the solution was allowed to warm to room temperature.

2-Aminobenzenesulfonic acid (0.11 mol, 19.05 g) was added to the solution and the pH was maintained at 7 by addition of 2 N NaOH. The reaction mixture was stirred at room temperature for 6 hours. The solution was then salted to 20% with NaCl. The resulting precipitate was filtered, washed, and dried.

The product of step (2) had the formula:

Stage (iii)

The product of step (ii) above (33 g, 0.025 mol at 70% concentration) was dissolved in water (300 mL) and the pH was adjusted to 12.0 by addition of NaOH. The solution was heated to 90 °C for 8 hours, maintaining the pH at 12.0 by addition of 2 N NaOH. Then the pH was lowered to 7.0 by addition of concentrated HCl and the mixture was stirred to cooled to room temperature. The solution was salted with NaCl to 20% w/w and the resulting precipitate was isolated by filtration.

The solid was purified by dialysis. Finally, the purified compound was converted to the ammonium salt by ion exchange solution to give the title product.

ink

Tine (1) was prepared by dissolving 2 parts of dye (1) in 98 parts of a mixture comprising 90 parts of water and 10 parts of 2-pyrrolidone. The pH of the ink was 7.0.

Inkjet printing

Ink 1 was applied to plain paper using a Hewlett Packard HP 660C inkjet printer, yielding prints that had a light magenta tint.

The optical density of the resulting prints was 1.2 to 1.3 as measured using an X-Rite densitometer.

The prints showed excellent lightfastness. After 64 hours of exposure in an Atlas weatherfastness tester, the density of the prints was reduced by only 10%. EXAMPLE 2 Dye (2)

Dye (2) was prepared as described in Example 1 except that the 2-aminobenzenesulfonic acid used in step (ii) was replaced by 4-aminobenzoic acid.

ink

Ink (2) was prepared by dissolving 2 parts of dye (2) in 98 parts of a mixture comprising 90 parts of water and 10 parts of 2-pyrrolidone. The pH of the ink was 7.0.

Inkjet printing

Ink (2) was applied to plain paper using an inkjet printer as described in Example 1 to obtain prints having a hue of light magenta. The optical density and lightfastness of the prints were measured as described in Example 1.

The prints showed excellent lightfastness. EXAMPLE 3 Dye (3)

The dye (3) was prepared as described in Example 1 except that the 2-aminobenzenesulfonic acid used in step (ii) was replaced by 2-amino-5-sulfobenzoic acid.

ink

Ink (3) was prepared by dissolving 2 parts of dye (3) in 98 parts of a mixture containing 90 parts of water and 10 parts of 2-pyrrolidone. The pH of the ink was 7.0.

Inkjet printing

Ink (3) was applied to plain paper using an inkjet printer as described in Example 1 to obtain prints having a light magenta hue. The optical density and lightfastness of the prints were measured as described in Example 1.

The prints showed excellent lightfastness. EXAMPLE 4 Dye (4)

Dye (4) was prepared as described in Example 1 except that the 2-aminobenzenesulfonic acid used in step (ii) was replaced by 3-amino-2-methylbenzoic acid.

ink

Ink (4) was prepared by dissolving 2 parts of dye (4) in 98 parts of a mixture containing 90 parts of water and 10 parts of 2-pyrrolidone. The pH of the ink was 7.0.

Inkjet printing

Ink (4) was applied to plain paper using an ink jet printer as described in Example 1, thus obtaining prints having a light magenta hue. The optical density and light fastness of the prints were measured as described in Example 1.

The prints showed excellent lightfastness. EXAMPLE 5 Dye (5)

Dye (5) was prepared as described in Example 1, except that the 2-aminobenzenesulfonic acid used in step (ii) was replaced by 5-amino-2-methylbenzenesulfonic acid.

ink

Ink (5) was prepared by dissolving 2 parts of dye (5) in 98 parts of a mixture containing 90 parts of water and 10 parts of 2-pyrrolidone. The pH of the ink was 7.0.

Inkjet printing

Ink (5) was applied to plain paper using an ink jet printer as described in Example 1 to obtain prints having a light magenta hue. The optical density and light fastness of the prints were measured as described in Example 1. The prints had excellent light fastness. EXAMPLE 6 Dye (6)

Dye (6) was prepared as described in Example 1 except that the 2-aminobenzenesulfonic acid used in step (ii) was replaced by intermediate (1) of the formula: Intermediate (1)

was replaced.

The intermediate (1) was prepared as follows:

N-Acetylsulfanilyl chloride (116.5 g, 0.5 mol) was stirred in water (300 mL). To this was added 4-(3-aminopropyl)morpholine (108.15 g, 0.75 mol) dropwise over about 30 minutes. The reaction mixture was then stirred at room temperature for 12 hours. Concentrated HCl (100 mL) was added and the solution was heated to 70 °C for 5 hours. After that, the pH was raised to 7 by addition of concentrated NaOH and the solution was salted to 20% with NaCl. The The resulting precipitate was filtered, washed and dried to give the title product. The yield was determined to be 81.5%.

ink

Ink (6) was prepared by dissolving 2 parts of dye (6) in 98 parts of a mixture comprising 90 parts of water and 10 parts of 2-pyrrolidone. The pH of the ink was 7.0.

Inkjet printing

Ink (6) was applied to plain paper using an inkjet printer as described in Example 1 to obtain prints having a light magenta hue. The optical density and lightfastness of the prints were measured as described in Example 1.

The prints showed excellent lightfastness. EXAMPLE 7 Dye (7)

The dye (7) was prepared as described in Example 1, except that the 2-aminobenzenesulfonic acid used in step (ii) was replaced by the intermediate (2) of the formula: Intermediate (2)

was replaced.

Intermediate (2) was prepared as follows:

p-Aminobenzenesulfatoethylsulfone (0.14 mol, 39.34 g) and N-acetylethylenediamine (0.42 mol, 47.7 g) were added to water. The resulting mixture was heated to 60 degrees for 4 hours while maintaining the pH at 8.5 by adding aqueous sodium hydroxide solution. Then, water was removed from the mixture by distillation to obtain a brown oil which crystallized upon standing. The crystalline solid was slurried in a small amount of water, isolated by filtration, washed with ethanol and sucked dry to leave the title product (yield = 22.21 g).

ink

Ink (7) was prepared by dissolving 2 parts of dye (7) in 98 parts of a mixture comprising 90 parts of water and 10 parts of 2-pyrrolidone. The pH of the ink was 7.0.

Inkjet printing

Ink (7) was applied to plain paper using an inkjet printer as in Example 1 to obtain prints having a light magenta hue. The optical density and lightfastness of the prints were measured as in Example 1.

The prints have excellent lightfastness.

EXAMPLE 8

The inks described in Tables I and II can be prepared where the dye described in the first column is the dye prepared in the example above with the same number. The numbers given in the second column below refer to the number of parts of the relevant ingredient and all parts are parts by weight. The inks can be applied by thermal or piezoelectric ink jet printing.

The following abbreviations are used in Tables I and II:

PG = Propylene glycol

NMP = N-methylpyrrolidone

IPA = isopropanol

2P = 2-pyrrolidone

P12 = Propane-1,2-diol

CET = cetylammonium bromide

TBT = tertiary butanol

DEG = diethylene glycol

DMK = dimethyl ketone

MEOH = methanol

MIBK = Methyl isobutyl ketone

BDL = butane-2,3-diol

PHO = Na₂HPO₄ and

TDG = 1,3-bis(2-hydroxyethyl)urea TABLE I TABLE I (continued) TABLE II TABLE II (continued)

Claims (11)

1. Compound of formula (1): Formula 1) wherein: A is N, C-Cl, C-CN or C-NO₂; L¹ is -OR³; Z -O-, -S- or -NR²- is; R¹ and R² are each independently H or optionally substituted alkyl; R³ is H or alkyl; each W is independently -CO₂Q or -SO₃Q; each X is independently an optionally substituted amino group or a group substituted with an optionally substituted amino group; each Y is independently halogen, hydroxy, nitro, cyano, optionally substituted alkyl, optionally substituted alkoxy, optionally substituted aryl, optionally substituted aralkyl, -SRa, -CORa, -COORa, -SO₃Ra or -SORa; Ra is C₁₋₄alkyl optionally substituted by carboxy, sulfo, hydroxy, nitro, cyano or halogen ; each Q is independently ammonium or substituted ammonium ; m, n and p each independently have a value from 0 to 3; and (m + n + p) has a value from 0 to 5. 2. A compound according to claim 1, wherein each Y is independently halogen, hydroxy, nitro, cyano, C1-4 alkyl, C1-4 alkoxy, -SRa, -CORa, -COORa, -SO3Ra or SORa wherein Ra is optionally substituted C1-4 alkyl where the optional substituents are selected from carboxy, sulfo, hydroxy, nitro, cyano and halogen. 3. A compound according to claim 1 or claim 2, wherein the optionally substituted amino groups mentioned in the definition of X have the formula -NR⁴R⁵ wherein R⁴ and R⁵ are each independently H or optionally substituted alkyl or R⁴ and R⁵ together with the nitrogen atom to which they are attached form a 5- or 6-membered ring. 4. A compound according to any preceding claim, wherein: A is N; m is 0, 1 or 2; n is 0 or 1; p is 0 or 1; X has the formula -NR⁴R⁵ or is a group substituted by -NR⁴R⁵; Y is halogen, hydroxy, cyano, C1-4 alkyl, C1-4 alkoxy, -SRa, -CORa, -COORa, -SO3 Ra or -SORa; R⁴ and R⁵ are each independently H or optionally substituted alkyl or R⁴ and R⁵ together with the nitrogen atom to which they are attached form a 5- or 6-membered ring; and Ra is as defined in claim 2. 5. A compound according to any preceding claim of formula (3): Formula (3) wherein: Z is -O-, -S- or -NR⁸-; R⁸ is C₁₋₄alkyl optionally substituted by hydroxy, carboxy, sulfo or cyano; L² is -OR⁹; R&sup9; is H or C1-4 alkyl; each W is independently -CO₂Q or -SO₃Q; each X¹ is -NR⁴R⁵, -SO₂-NR⁴R⁵, -SO₂(C₁₋₁₀alkylene)-NR⁴R⁵, or C₁₋₆alkyl substituted by -NR⁴R⁵; each Y¹ is independently Cl, nitro, cyano, C₁₋₁₀alkyl or C₁₋₁₀alkyl substituted by hydroxy, carboxy, sulfo or C₁₋₆alkoxy; Q is ammonium or substituted ammonium; m, n and p are each independently 0 or 1 ; (m + n + p) is 1, 2 or 3 and R⁴ and R⁵ are as defined in claim 4, provided that n is 1 when m is 0. 6. A compound according to claim 4 or 5, wherein -NR⁴R⁵ has the formula (2): Formula (2) wherein: M is an alkyl bonding group and R6 and R7 are each independently H, C1-6 alkyl or C1-6 alkyl substituted by hydroxy, carboxy, sulfo, amino or C1-4 alkoxy. 7. Ink comprising: (a) 0.01 to 30 parts of a compound according to any one of claims 1 to 6, except that Q is any cation; and (b) 70 to 99.99 parts of a medium comprising component (i), (ii) or (iii): (i) a mixture of water and an organic solvent; (ii) an organic solvent free from water, or (iii) a solid with a low melting point; where all parts are parts by weight and the number of parts of (a) + (b) = 100. 8. The ink of claim 7, wherein Q is sodium, ammonium or substituted ammonium. 9. A method of printing an image on a substrate, comprising applying an ink according to claim 7 or 8 to the substrate using an inkjet printer. 10. Paper, overhead projector glass or textile material printed with an ink according to claim 7 or 8 or by a method according to claim 9. 11. An inkjet printer cartridge containing an ink according to claim 7 or 8.